CN117615994A

CN117615994A - Light-scattering silica particles and method for producing light-scattering silica particles

Info

Publication number: CN117615994A
Application number: CN202280047950.2A
Authority: CN
Inventors: 片山肇; 近藤雅史; 福本浩大; 高野裕里子; 有光慎之介; 村上武司; 东贤志; 山隅大辅
Original assignee: Agc Silicon Technology Co ltd; Asahi Glass Co Ltd
Current assignee: Agc Silicon Technology Co ltd; AGC Inc
Priority date: 2021-07-07
Filing date: 2022-06-29
Publication date: 2024-02-27
Also published as: KR20240032747A; EP4368573A1; JPWO2023282158A1; US20240122818A1; WO2023282158A1

Abstract

The present invention provides particles having high scattering properties for both visible light and ultraviolet light and also having a smooth touch and high safety. The light-scattering silica particles of the present invention are light-scattering silica particles having a closed-cell structure, wherein the inside of each of the particles has a plurality of hollow portions, 50% of the particles have a particle diameter of 1 to 500 [ mu ] m, and an average circularity of 0.8 or more, and the amount of silica per unit measurement cross-sectional area when the light-scattering silica particles are used is 20mg/cm ² Is a water cake of (2)The reflectance A at the ultraviolet wavelength of 310nm is 30% or more.

Description

Light-scattering silica particles and method for producing light-scattering silica particles

Technical Field

The present invention relates to light-scattering silica particles and a method for producing light-scattering silica particles.

Background

Light scattering refers to: at the interface of two phases of different refractive index, the direction of light propagation changes. Particles in which such light scattering occurs are used as fillers in various fields of cosmetics, paints, optical members, and the like.

The degree of light scattering varies with the wavelength of light, the particle size, and the refractive index of the particle and its surrounding environment.

In order to produce particles having high light scattering properties, for example, the size of the particles is reduced to increase the interface, or the particles are made to contain a high refractive material such as titanium dioxide or zinc oxide, or hollow portions (void portions) are formed inside the particles to increase the refractive index difference from the surrounding environment.

On the other hand, when the particles are used as a filler, the feeling of use is also important, and particularly, cosmetics are required to have good touch feeling such as smoothness to the skin.

As a method for improving the touch feeling by providing the particles with light scattering properties, a method is known in which a high refractive material such as titanium dioxide or zinc oxide is contained in spherical particles. For example, patent document 1 proposes a spherical silica containing titanium dioxide having an average particle diameter of 1 to 10 μm, wherein silica gel is formed by dispersing SiO into a silica gel matrix ₂ Titanium dioxide having an average particle diameter of 0.01 to 0.5 μm is dispersed in an amount of 10 to 60% by weight based on the total amount of titanium dioxide.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 11-322324

Disclosure of Invention

Problems to be solved by the invention

When the particles contain a high refractive material such as titanium dioxide or zinc oxide, the scattering properties for visible light can be improved, but these high refractive materials absorb ultraviolet rays, so that the scattering properties for ultraviolet rays are low, and the degree of light scattering varies depending on the wavelength of light. In addition, when particles containing a metal element such as titanium dioxide are used for applications such as cosmetics where the particles directly contact skin or may enter the body through eyes, mouth, and nose, there is a concern about safety, and titanium dioxide and the like have photocatalytic properties, so that there is a concern about deterioration of other raw materials.

Accordingly, an object of the present invention is to provide particles having both light scattering properties at a wide range of wavelengths and good touch properties, specifically, particles having high scattering properties for both visible light and ultraviolet rays and also having high safety to smooth touch.

Solution for solving the problem

The present inventors have found that, when studied in view of the above problems: the present invention has been completed by solving the above-described problems by using spherical silica particles in which a plurality of hollow portions having a closed-cell structure are formed in the particles.

The present invention relates to the following (1) to (16).

(1) A light-scattering silica particle having light scattering properties,

A plurality of hollow parts with closed pore structures are arranged inside the particles,

the cumulative 50% particle diameter based on the volume of the light-scattering silica particles is 1 to 500 μm, and the average circularity is 0.80 or more,

when the light-scattering silica particles are used, the amount of silica per unit measured cross-sectional area is 20mg/cm ² The reflectance A of the water cake at the ultraviolet wavelength of 310nm is more than 30%.

(2) The light-scattering silica particles according to the above (1), wherein the oil absorption of the light-scattering silica particles is 100cm ³ And/or 100 g.

(3) The light-scattering silica particles according to the above (1) or (2), wherein the hollow portion is defined by hollow particles.

(4) The light-scattering silica particles according to any one of (1) to (3), wherein the hollow portion has a size of 200nm to 50. Mu.m.

(5) The light-scattering silica particles according to any one of the above (1) to (4), wherein the amount of silica per unit measurement cross-sectional area when the light-scattering silica particles are used is 20mg/cm ² The reflectance B of the water cake at the visible light wavelength of 600nm is more than 30%.

(6) The light-scattering silica particles according to the above (5), wherein the difference (A-B) obtained by subtracting the reflectance B from the reflectance A is 3% or more.

(7) The light-scattering silica particles according to any one of (1) to (6), wherein 1 or 2 or more kinds selected from the group consisting of silicones, silylating agents, fatty acids having 12 or more carbon atoms and metal salts thereof, and higher alcohols having 14 or more carbon atoms are supported on the surfaces of the light-scattering silica particles.

(8) A method for producing light-scattering silica particles, which is a method for producing light-scattering silica particles having light scattering properties,

the hollow-portion-forming particles are dispersed in a silica precursor dispersion or a silica precursor solution, and emulsion treatment is performed to obtain droplets, and the droplets are solidified.

(9) The method for producing light-scattering silica particles according to the above (8), wherein the hollow-forming particles are dispersed in the silica precursor dispersion or the silica precursor solution in an amount ranging from 0.1 to 40 mass%.

(10) The method for producing light-scattering silica particles according to the above (8) or (9), wherein the hollow-portion-forming particles are hollow particles.

(11) The method for producing light-scattering silica particles according to the above (10), wherein the hollow particles are at least 1 kind of hollow silica particles and glass hollow spheres.

(12) The method for producing light-scattering silica particles according to the above (10) or (11), wherein the hollow portion inside the hollow particles has a size of 200nm to 50. Mu.m.

(13) The method for producing light-scattering silica particles according to the above (8) or (9), wherein the hollow-portion-forming particles are template particles, the droplets are solidified, the template particles are removed, and the silica particles are calcined at 800 to 1300 ℃.

(14) The method for producing light-scattering silica particles according to (13), wherein the size of the template particles is 200nm to 50. Mu.m.

(15) The method for producing light-scattering silica particles according to any one of (8) to (14), wherein 1 or 2 or more kinds selected from the group consisting of silicones, silylating agents, fatty acids having 12 or more carbon atoms and metal salts thereof, and higher alcohols having 14 or more carbon atoms are attached to the surface of particles obtained by solidifying the liquid droplets.

(16) A cosmetic comprising the light-scattering silica particles according to any one of the above (1) to (7).

ADVANTAGEOUS EFFECTS OF INVENTION

The light-scattering silica particles of the present invention are light-scattering for both visible light and ultraviolet light, and have smooth touch feeling upon touch. Further, since the hollow portion inside the particle has a closed-cell structure, not only the hollow portion is immersed in a liquid such as water or oil, but also light scattering properties can be exhibited when the light scattering silica particles are used in either a dry state or a wet state. Further, since it is made of silica, the safety is also high. Thus, it can be suitably used for cosmetics.

Drawings

Fig. 1 is a photograph showing a scanning electron microscope image (SEM image) of the light-scattering silica particles obtained in example 2.

Fig. 2 is a photograph showing a scanning electron microscope image (SEM image) of the silica particles obtained in example 6.

Fig. 3 is a photograph showing an optical microscope image of the light scattering silica particles obtained in example 3 and the silica particles of examples 4 and 6.

Fig. 4 is a view showing the shielding properties of the light scattering silica particles obtained in example 3 and the porous spherical silica particles of example 4.

FIG. 5 is a graph showing the reflectance spectrum of the light-scattering silica particles obtained in example 3 immediately after the preparation of a 1% aqueous slurry.

Detailed Description

The present invention will be described below, but the present invention is not limited to the examples described below.

In this specification, "mass" and "weight" have the same meaning.

< light-scattering silica particles >

The light-scattering silica particles of the present invention have a plurality of hollow portions having a closed-cell structure in the interior of the particles,the cumulative 50% particle diameter on a volume basis is 1 to 500 μm, and the average circularity is 0.80 or more. When the light-scattering silica particles are used, the amount of silica per unit measurement cross-sectional area is 20mg/cm ² The reflectance A of the water cake at the ultraviolet wavelength of 310nm is more than 30%.

The "hollow portion having a closed cell structure" existing inside the particles means: voids that exist independently inside the particles and do not communicate with the outside.

The particle powder was observed with an optical microscope (for example, morphogi 4, manufactured by Malvern corporation) in a state of being immersed in boiled linseed oil (boiled linseed oil), and it was confirmed whether or not the inside of the particle had a hollow portion. In the case where the particle has a hollow portion inside, a scattering body having a contrast different from the surrounding is observed.

Whether or not the hollow portion inside the particle has a closed cell structure (whether or not it has an open cell structure) can be confirmed by immersing the particle in a liquid such as water, and when the liquid does not enter the hollow portion, it can be said that the particle has a closed cell structure. When the liquid is immersed in the hollow portion, the refractive index of the hollow portion is similar to the surrounding environment (silica, water, oil, etc. dispersion medium constituting the particles), and the particles are in a semitransparent state. If the air phase of the hollow portion is maintained, light is reflected in the same state as when bubbles are present in the liquid, and the liquid looks whitish.

Since the hollow portion included in the light-scattering silica particles of the present invention is closed, the liquid does not penetrate into the hollow portion, and therefore, when the light-scattering silica particles are used in either a dry state or a wet state, light scattering can be exhibited.

The light-scattering silica particles of the present invention are produced by using silica (SiO ₂ ) Particles as a main component. In the present specification, "silica as a main component" specifically means that the concentration of silica is 80 mass% or more, preferably 90 mass% or more, and more preferably 95 mass% or more. The upper limit is theoretically 100 mass%. The content of silica constituting the light-scattering silica particles is preferably less than 100 mass%, more preferably 99 mass% or less. As a residual quantityAlkali metal oxides, carbon, and the like can be cited.

In the porous silica, when the pore diameter is sufficiently smaller than the wavelength of light, light is scattered at the interface between the outer surface of the silica particles and air, and therefore, the more the interface with air not in the pores is, the more light can be scattered. Therefore, since a plurality of hollow portions (voids) having a size equal to or larger than the wavelength of ultraviolet light are present in the particles, the hollow portions and the silica layer around the hollow portions function as interfaces for scattering light, and therefore, light scattering properties are improved, and as a result, shielding properties are improved.

The size of the hollow portion contained in the light-scattering silica particles is preferably 200nm to 50. Mu.m. The size of the hollow portion refers to the length of the long axis of the hollow portion, and the diameter at which the smallest circumscribed circle circumscribed with the hollow portion observed by SEM or TEM is drawn is regarded as the size of the hollow portion. By including a hollow portion having a size of 200nm or more in the particles, scattering of light can occur, and the size of the hollow portion is preferably 50 μm or less in view of the size (particle diameter) of the light-scattering silica particles that can be produced.

The size of the hollow portion in the particle is more preferably 230nm or more, particularly preferably 250nm or more. In addition, when the size of the hollow portion is small, since a plurality of hollow portions can be contained in the particles, the scattering interface increases, and therefore, the size of the hollow portion is more preferably 10 μm or less, further preferably 1 μm or less, and particularly preferably 0.5 μm or less. When the hollow portion is 200 to 400nm in size, ultraviolet light is scattered preferentially over visible light.

The number of hollow portions may be 2 or more in one particle, and may be appropriately adjusted according to the size of the light scattering silica particles and the size of the hollow portions.

The volume ratio of the plurality of hollow portions in the light-scattering silica particles is preferably 40% or less of the volume of the light-scattering silica particles. The interface can be increased by increasing the number of hollow portions in the particles, but even if the hollow portions are too many, the scattering effect in which light scattering is balanced is not changed. The volume ratio of the plurality of hollow portions is more preferably 30% or less, still more preferably 20% or less, and particularly preferably 10% or less. The lower limit is not particularly limited as long as the effect of the present invention can be obtained, and is preferably 0.1% or more, more preferably 0.5% or more, and still more preferably 1% or more. The specific gravity of the particles can also be reduced by increasing the volume fraction of the hollow portions within the particles.

The volume ratio of the hollow portion of the light scattering silica particles was expressed as a percentage by dividing the total volume occupied by the hollow portion by the sum of the volume occupied by silica and the total volume occupied by the hollow portion, and was obtained as follows.

The volume ratio of the hollow portion was determined by using argon (Ar) gas for the light-scattering silica particles, and the density (g/cm) ³ ) And true density of silica (2.2 g/cm) ³ ) The calculation was performed to obtain the result. The measured density was set to ρ (g/cm ³ ) When the volume ratio of the hollow portion is 100-100 xρ/2.2 (%).

The Ar gas impermeable silica layer may be a substantially water impermeable silica layer. When the ratio of the hollow portion is large, the volume ratio of the hollow portion may be estimated by using the density difference.

In the present invention, the silica around the hollow portion may be porous silica or nonporous silica. When used as a cosmetic, porous silica absorbs sebum and sweat, and thus can improve the feel of use. Since the hollow portion of the light-scattering silica particles of the present invention has a closed-cell structure, the scattering properties of light do not change even when the particles absorb sebum or sweat. In some cases, it is preferable to make silica pore-free in cosmetic applications, in order to place importance on smoothness. When light-scattering silica particles are used as a filler in a resin, if porous, there is a possibility that bubbles may be generated and viscosity may be increased, and therefore, silica is preferably made non-porous.

In the present invention, the pore volume of the light-scattering silica particles is preferably 4cm ³ /g toAnd (3) downwards. The pore volume herein means a pore volume derived from pores having a pore diameter of 1 to 100 nm. By having pores (voids) around the hollow portion, the apparent particle density becomes small. That is, if the porous silica is used, the light-scattering silica particles are lightweight particles, and the touch feeling is improved. If the pore volume is too large, the particle strength may be lowered and the use is limited, so that it is preferably 4cm ³ And/g or less.

The pore volume is more preferably 3cm ³ Preferably not more than/g, more preferably 2.5cm ³ And/g or less. The lower limit of the pore volume of the light-scattering silica particles is not particularly limited, but is preferably 0.1cm in the case of producing porous silica ³ Preferably at least 0.8cm ³ Preferably 1.0cm or more, and more preferably 1.0cm ³ And/g.

The pore volume may be calculated by a nitrogen adsorption method and by a BJH method.

The oil absorption of the light-scattering silica particles of the present invention is preferably 100cm ³ And/or 100 g. If the oil absorption is 100cm ³ With the ratio of 100g or more, the apparent density can be reduced to form lightweight particles, and the high shielding property can be maintained even when a small amount of sebum is absorbed, so that the composition can be suitably used for cosmetic applications.

The oil absorption is more preferably 150cm ³ 100g or more, more preferably 200cm ³ 100g or more, particularly preferably 250cm ³ And/or 100 g. The upper limit of the oil absorption is not particularly limited, but is preferably 1000cm from the viewpoint of particle strength ³ Less than 100g, more preferably 800cm ³ Preferably less than 100g, more preferably 600cm ³ And/or less than 100 g.

The oil absorption can be measured in accordance with JIS K5101 (2004). Specifically, the whole sample is kneaded into one piece, and boiled linseed oil is added to the sample. The oil absorption is expressed as the volume of boiled linseed oil per 100g of the sample when the whole sample is changed to one piece. Hereinafter, the oil absorption amount by this measurement method will be simply referred to as the oil absorption amount.

The light scattering silica particles of the inventionThe specific surface area of the particles, as determined by the nitrogen adsorption method, is preferably 100m ² And/g. If the specific surface area is 100m ² Above/g, the active sites can be increased when used as a catalyst support.

The specific surface area is more preferably 200m ² Preferably at least/g, more preferably 250m ² Preferably at least 300m ² The upper limit of the ratio/g is not particularly limited.

The specific surface area can be calculated using the BET theory after the adsorption isotherm is obtained by the nitrogen adsorption method.

The size of the light scattering silica particles was calculated as a 50% volume conversion particle size using a particle size distribution measuring apparatus (for example, MT3300EXII manufactured by Microtrac BEL corporation) by a laser diffraction method. Hereinafter, the cumulative 50% particle diameter based on the volume of the particles is also referred to simply as "50% particle diameter".

50% particle diameter (D) ₅₀ ) In the range of 1 to 500. Mu.m. If 50% of the particle diameter (D ₅₀ ) When used as a filler, the filler exhibits good dispersibility and smooth touch, and thus gives an improved feeling in use. From the viewpoint of the feel of use of cosmetics when the light-scattering silica particles are used as cosmetic materials, 50% of the particles have a particle diameter (D ₅₀ ) Preferably 2 μm or more, more preferably 3 μm or more, and still more preferably 4 μm or more. The upper limit is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 20 μm or less, from the viewpoint of handleability as a filler.

The average circularity of the light-scattering silica particles is 0.80 or more. When the average circularity is 0.80 or more, the shape of the particles is substantially spherical, and thus the feeling to the skin becomes good, and the particles can be suitably used for various applications.

The average circularity of the silica particles is more preferably 0.90 or more, and still more preferably 0.95 or more. The upper limit of the circularity is not particularly limited, and is most preferably 1.

It should be noted that, the circularity can be calculated as follows: the area and the perimeter of the particle are obtained by using image analysis software attached to a particle image analysis device (for example, morphogi 4 manufactured by Malvern corporation) and are substituted into the following formula for calculation. The average circularity was obtained by obtaining an average value of 3 ten thousand particles.

Circularity = circumference of circle of equal projected area/circumference of particle

Circumference of circle with equal projected area: when a particle is observed from directly above, the area of the shadow of the particle mapped on the lower plane is obtained, and a circle having the same length as the area is calculated, and the length of the outline of the circle

Perimeter of the particles: the length of the outline of the shadow of the particle mapped on the underlying plane when the particle is viewed from directly above

In the present invention, the hollow portion in the light scattering silica particles is preferably defined by hollow portion forming particles. In the present specification, the hollow portion forming particles mean: in the production of light-scattering silica particles, particles are added to a raw material to form hollow portions. By defining the hollow portion by the hollow portion forming particles, the hollow portion can be easily made into a closed-cell structure, and when the light scattering silica particles are brought into contact with a liquid such as water or oil, the liquid can be prevented from entering the hollow portion, and the shielding property due to light scattering can be maintained. In the case of using the hollow-forming particles based on an organic substance, the closed-cell structure can be defined by forming the particles containing the hollow-forming particles, removing the hollow-forming particles by calcination or dissolution treatment, and then performing heat treatment at a high temperature to cover the periphery of the hollow with a dense phase.

Examples of the hollow-forming particles include hollow particles and template particles.

Examples of the hollow particles include hollow silica particles, glass hollow spheres, and resin hollow particles. The size of the hollow portion of the hollow particle is substantially equal to the size of the hollow portion of the light scattering silica particle. By using hollow particles as the hollow portion forming particles, closed-cell hollow portions can be formed even without performing calcination treatment, and the porous portions are not lost by calcination, so that light scattering particles having high oil absorption can be provided.

Examples of the template particles include resin particles and acid-soluble inorganic particles, and examples of the acid-soluble inorganic particles include magnesium carbonate, magnesium hydroxide, calcium carbonate, and calcium hydroxide. The size of the template particles was substantially the same as the size of the hollow portions in the light-scattering silica particles.

Among them, the hollow portion is particularly preferably defined by hollow particles from the viewpoint of easy definition of the hollow portion into a dense closed-cell structure.

The light-scattering silica particles of the present invention may have a surface treatment agent supported on the surface thereof. By supporting the surface treatment agent, the particles can be rendered hydrophobic and uniformly dispersed in the resin or solvent.

Examples of the surface treating agent include silicone, silylating agent, fatty acid having 12 or more carbon atoms, metal salt thereof, and higher alcohol having 14 or more carbon atoms, and combinations of 1 or 2 or more of them.

Examples of the silicone include dimethyl silicone, methyl hydrogen silicone, methyl phenyl silicone, alkyl-modified silicone, fatty acid-modified silicone oil, polyether-modified silicone oil, alkoxy-modified silicone oil, methanol-modified silicone oil, amino-modified silicone oil, fluorine-modified silicone oil, and silicone oil such as terminal-reactive silicone oil.

Examples of the silylating agent include chlorosilanes such as dimethyldichlorosilane, trimethylchlorosilane, phenyldimethylchlorosilane, t-butyldimethylchlorosilane, and vinyldimethylchlorosilane; alkoxysilanes such as methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, N-butyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, isobutyltriethoxysilane, decyltriethoxysilane, vinyltriethoxysilane, γ -methacryloxypropyl trimethoxysilane, γ -glycidoxypropyl trimethoxysilane, γ -mercaptopropyl trimethoxysilane, and N-phenyl- γ -aminopropyl trimethoxysilane; silazanes such as hexamethyldisilazane, hexaethyldisilazane, hexacyclohexyldisilazane, hexaphenyldisilazane, divinyl tetramethyl disilazane, and dimethyl tetravinyl disilazane.

Examples of the fatty acid having 12 or more carbon atoms and the metal salt thereof include long-chain fatty acids such as lauric acid, tridecylic acid, dodecylic acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, arachidonic acid, and behenic acid; salts of the fatty acids with metals such as zinc, iron, magnesium, aluminum, calcium, sodium, lithium, etc.

Examples of the higher alcohol having 14 or more carbon atoms include myristyl alcohol, cetyl alcohol, 2-hexyldecyl alcohol, stearyl alcohol, cetostearyl alcohol, oleyl alcohol, linoleyl alcohol, linolenyl alcohol (linolenyl alcohol), isostearyl alcohol, chikunguyl alcohol, arachidyl alcohol, octyldodecanol, ethylene glycol monostearate, stearic monoethanolamide, glycerol monostearate, squalyl alcohol, shark alcohol, behenyl alcohol, decyltetradecyl alcohol, and tetracosanol.

Among the above surface treatment agents, the light scattering silica particles used in the cosmetic field are preferably loaded with a fatty acid having 12 or more carbon atoms and a metal salt thereof, or a higher alcohol having 14 or more carbon atoms, more preferably a higher alcohol having 14 or more carbon atoms, from the viewpoint of being excellent from natural sources to the environment and the human body.

The higher alcohol having 14 or more carbon atoms is preferably a higher alcohol having 14 to 36 carbon atoms from the viewpoint of being industrially easily available and imparting water repellency to the particle surface. The number of carbon atoms of the higher alcohol is more preferably 16 or more, still more preferably 18 or more, particularly preferably 20 or more, and further more preferably 30 or less, still more preferably 28 or less, particularly preferably 24 or less.

The higher alcohol may be either a straight chain or branched chain, or may be either saturated or unsaturated.

The number of hydroxyl groups in the higher alcohol having 14 or more carbon atoms may be 1 or more. The hydroxyl number is preferably 5 or less, more preferably 3 or less in terms of practical use.

The higher alcohol having 14 or more carbon atoms may have a long-chain alkyl group which is optionally unsaturated and a hydroxyl group. Wherein a linking group may be present between the optionally unsaturated long chain alkyl group and the hydroxyl group. Examples of the linking group include an ester bond, an etheric oxygen atom, and an amide bond.

When the light-scattering silica particles contain a surface treatment agent, the loading of the surface treatment agent is preferably 1 to 6. Mu. Mol/m, relative to the specific surface area of the silica particles ² . When the amount of the surface treatment agent is in the above range, the surface treatment agent has sufficient hydrophobicity.

The loading of the surface treatment agent is more preferably 1.2mol/m ² The above is more preferably 1.5. Mu. Mol/m ² The above is more preferably 5. Mu. Mol/m ² Hereinafter, it is more preferably 4. Mu. Mol/m ² The following is given.

The light-scattering silica particles of the present invention have a silica content per unit measurement cross-sectional area of 20mg/cm when the light-scattering silica particles are used ² The reflectance A of the water cake at the ultraviolet wavelength of 310nm is more than 30%. When the reflectance a based on the measurement is 30% or more, the ultraviolet light scattering property is exhibited, and it is found that water does not penetrate into the hollow portions of the light scattering silica particles, and therefore the light scattering property can be exhibited in both the dry state and the wet state.

The reflectance a is preferably 35% or more, more preferably 40% or more, and further preferably 45% or more. In order to exhibit the desired effect in a small amount, the higher the reflectance a is, the more preferable, and the upper limit is not particularly limited.

In addition, regarding the light-scattering silica particles of the present invention, the amount of silica per unit measured cross-sectional area when the light-scattering silica particles are used is 20mg/cm ² Is at visible light wavelength 600The reflectance B at nm is preferably 30% or more. When the reflectance B based on the measurement is 30% or more, it is known that the silica particles have light scattering properties with respect to visible light, and water does not enter the hollow portions of the light scattering silica particles, so that the silica particles can exhibit light scattering properties in both a dry state and a wet state.

The reflectance B is preferably 35% or more, more preferably 40% or more. Further, since the index is an index indicating whiteness and shielding properties of the particles, the higher the reflectance B is, the more preferable, and the upper limit is not particularly limited.

In the present specification, the reflectance refers to a relative reflectance when the reflectance of a standard white board (barium sulfate) is set to 100%, and the reflectance when all reflected light (a value obtained by adding regular reflected light and diffuse reflected light) is measured using an integrating sphere. The reflectance can be obtained by measuring the silica water cake using an ultraviolet-visible near infrared spectrophotometer (for example, UV-3100PC, manufactured by Shimadzu corporation) as a measuring device.

Specifically, water is added to and mixed with the powder of the light-scattering silica particles to prepare a silica water cake, and the amount of silica per unit measurement cross-sectional area is 20 to 30mg/cm ² The water cake was filled in a dish for powder samples, and the reflectance (reflectance a) of the water cake at wavelengths of 310nm and 600nm was measured using an ultraviolet-visible near-infrared spectrophotometer. Thereafter, reflectance (reflectance b) at wavelengths of 310nm and 600nm was measured without loading a sample into a cuvette, and the interpolation values of the reflectance a and the reflectance b were calculated to give a silica amount of 20mg/cm per unit measurement cross-sectional area ² Reflectivity at that time.

The difference (A-B) obtained by subtracting the reflectance B at the visible light wavelength of 600nm from the reflectance A at the ultraviolet wavelength of 310nm is preferably 3% or more. When the difference a-B is 3% or more, the reflected light of a short wavelength becomes large, and thus the reflected light is slightly bluish to give a transparent feeling.

The difference a-B is more preferably 5% or more, and still more preferably 7% or more. In the case where blue is to be emphasized, the higher the difference a-B is, the more preferable, and the upper limit is not particularly limited.

The light-scattering silica particles of the present invention are preferably: the reflectance a and the reflectance B based on the above measurement remained the same even after being kept in the state of the water cake for 1 week.

In addition, regarding the light-scattering silica particles of the present invention, L was mixed with the light-scattering silica particles in a proportion of 40 mass% ^* a ^* b ^* A in the color system ^* When a mixed powder is obtained from a reddish brown iron (III) oxide powder having a value of 14 to 15 (for example, manufactured by Kanto chemical Co., ltd., high purity (Japanese: deer grade)), a of the mixed powder is obtained ^* The value is preferably 6.0 or less. L is the same as ^* a ^* b ^* The color system is standardized by the International Commission on illumination (CIE) in 1976.

The above measurement method enables evaluation of the light scattering properties of the light scattering silica particles in a dry state. If a is the above ^* When the value is 6.0 or less, it can be evaluated that the dry powder has high scattering property of visible light and excellent shielding ability.

The above a ^* The value is more preferably 5.0 or less, still more preferably 4.5 or less, particularly preferably 4.0 or less, and a is further preferably not more than ^* The smaller the value, the more preferable, and therefore, the lower limit value is preferably 0.

Powder a ^* The value can be measured using, for example, a spectrocolorimeter (for example, SE7700, manufactured by japan electric color industry). In the measurement by the spectrocolorimeter, the mixed powder was charged so that the thickness became 7.5mm or more, and the measurement was performed.

The dynamic friction coefficient and the static friction coefficient of the light-scattering silica particles of the present invention are each preferably 0.60 or less. When the dynamic friction coefficient is 0.60 or less, the particles slide with low resistance, and therefore, in the case of use in cosmetics, the touch feeling upon contact with the skin is improved, and therefore, a smooth sliding feeling can be exhibited. The dynamic friction coefficient is more preferably 0.55 or less, still more preferably 0.50 or less, and particularly preferably 0.40 or less. The lower limit of the dynamic friction coefficient is not particularly limited, but is preferably 0.05 or more, more preferably 0.10 or more, and still more preferably 0.15 or more.

When the static friction coefficient is 0.60 or less, the particles start to slide with low resistance, and therefore, in the case of use in cosmetics, the touch feeling upon contact with the skin is improved. The static friction coefficient is more preferably 0.50 or less, and still more preferably 0.40 or less. The lower limit of the static friction coefficient is not particularly limited, but is more preferably 0.01 or more, still more preferably 0.05 or more, and particularly preferably 0.10 or more.

The coefficient of dynamic friction may be measured using a static/dynamic friction measuring machine (for example, "TL201Tt" manufactured by Trinity-Lab corporation). Specifically, the simulated fingers made of urethane were used as contacts, respectively, and the artificial leather was used as a coating substrate, and the volume per unit area was 0.8. Mu.L/cm in terms of the amount of adhesion ² In the method (2), hydrophobic silica particles are applied to artificial leather, and the artificial leather is operated under a load of 30gf and a scanning distance of 40mm to measure a coefficient of friction, and an average value in a range of 1000msec to 4000msec is used as a dynamic coefficient of friction.

The coefficient of static friction was measured by the same method as described above, and the maximum value in the range of 0msec to 1000msec was used as the coefficient of static friction.

< method for producing light-scattering silica particles >

The method for producing the light-scattering silica particles of the present invention comprises: the hollow-portion-forming particles are dispersed in a silica precursor dispersion or a silica precursor solution, and emulsion treatment is performed to obtain droplets, and the droplets are solidified.

First, a dispersion in which hollow-forming particles are dispersed in a silica precursor dispersion or a silica precursor solution is used as a dispersed phase, an organic phase containing a surfactant is used as a continuous phase, and the dispersed phase is mixed with the continuous phase and stirred to obtain an emulsion.

The dispersed phase and the continuous phase are emulsified by stirring, thereby obtaining a water-in-oil (W/O) emulsion (emulsion). In the continuous phase, the dispersed phase is formed into droplets, and hollow particles are present in the droplets of the silica precursor dispersion or the silica precursor solution.

The silica precursor dispersion or silica precursor solution is a solution obtained by dispersing or dissolving a silica precursor in a solvent. Examples of the silica precursor include sodium silicate, potassium silicate, lithium silicate, tetramethoxysilane, tetraethoxysilane, and tetrapropoxysilane. Examples of the solvent for dispersing or dissolving the silica precursor include water, methanol, ethanol, propanol, butanol, and other lower alcohols.

The concentration of the silica precursor is converted into SiO ₂ SiO of (2) ₂ The concentration meter is preferably in the range of 3 to 35 mass%. If SiO in the silica precursor dispersion or silica precursor solution ₂ When the conversion concentration is within the above range, the light scattering silica particles can be produced with high production efficiency.

SiO in the silica precursor dispersion or silica precursor solution is useful for obtaining particles having high productivity and high sphericity ₂ The concentration in terms of the amount is more preferably 5% by mass or more, still more preferably 7% by mass or more, and particularly preferably 10% by mass or more. Further, from the viewpoint of facilitating the obtainment of particles having a small particle diameter, it is more preferably 30% by mass or less, still more preferably 25% by mass or less, and particularly preferably 20% by mass or less.

In the case of using an aqueous sodium silicate solution as the silica precursor dispersion or the silica precursor solution, the ratio of silica to sodium in the aqueous sodium silicate solution is SiO ₂ /Na ₂ O (molar ratio) is preferably 2 to 4.SiO (SiO) ₂ /Na ₂ The aqueous sodium silicate solution having O (molar ratio) in the above range can be easily obtained, and examples thereof include sodium silicate No. 3 (manufactured by AGC Si-Tech Co., ltd., siO ₂ /Na ₂ O=3), sodium silicate No. 2 (AGC Si-Tech company, siO ₂ /Na ₂ O=2.5), sodium silicate No. 1 (manufactured by AGC Si-Tech company, siO ₂ /Na ₂ O=2), and the like.

The hollow-forming particles are not particularly limited as long as they can define a hollow inside the light-scattering silica particles, and examples thereof include hollow particles having a hollow inside, and template particles which are not provided with a hollow but can be removed by calcination and dissolution.

As the hollow particles, a substance which does not dissolve in the silica precursor dispersion or the silica precursor solution and does not absorb ultraviolet rays is used. The hollow particles are contained in the light-scattering silica particles, and the hollow portions of the light-scattering silica particles are defined by the hollow particles.

Examples of the hollow particles include hollow silica particles, glass hollow spheres, and resin hollow particles. Examples of the resin hollow particles include hollow particles formed of silicone resin, acrylic-styrene resin, and the like. The number of these may be 1 alone or 2 or more.

As the template particles, those which do not dissolve in an aqueous sodium silicate solution and which decompose by heat or dissolve by acid are used. The template particles are removed in the step of producing the light-scattering silica particles, and the hollow portions of the light-scattering silica particles are defined by the voids left after the removal.

Examples of the thermally decomposable template particles decomposed by heat include resin particles of polypropylene, acrylic, styrene, silicone, and the like. Examples of the acid-soluble template particles dissolved in an acid include magnesium hydroxide, magnesium carbonate, calcium hydroxide, and calcium carbonate. The number of these may be 1 alone or 2 or more. Among them, from the viewpoint of being able to dissolve and remove the template particles using sulfuric acid, at least 1 selected from the group consisting of magnesium hydroxide and magnesium carbonate is preferable. Sulfuric acid is a non-volatile acid, and is preferable from the viewpoints of safety and equipment protection, as compared with hydrochloric acid, nitric acid, hydrofluoric acid, and the like, which are volatile acids.

Among these, from the viewpoints of easiness of the production process and easiness of the production of closed cells, the hollow portion forming particles are preferably hollow particles covered with a dense shell, and more preferably at least 1 selected from the group consisting of hollow silica particles and glass hollow spheres.

The size of the hollow-forming particles may be appropriately selected in consideration of the size (particle diameter) of the light-scattering silica particles, the strength of the light scattering property to be sought, and the like.

Specifically, when the hollow-portion-forming particles are hollow particles, it is preferable to use hollow particles in which the size of the hollow portion in the hollow particles is in the range of 200nm to 50 μm. The size of the hollow portion is more preferably 230nm or more, still more preferably 250nm or more, still more preferably 10 μm or less, still more preferably 1 μm or less, and particularly preferably 0.5 μm or less.

The size of the hollow portion is the length of the long axis of the hollow portion, and the diameter at which the smallest circumscribed circle circumscribed to the hollow portion observed by SEM or TEM is drawn is set as the size of the hollow portion.

When the hollow particles contained in the light-scattering silica particles are excessively large, the scattering interface of light decreases and the scattering effect decreases. If the hollow particles are too large, spherical light-scattering silica particles are not easily obtained, and the touch feeling is deteriorated. 50% particle diameter of hollow particles (D ₅₀ ) Preferably 200nm to 50. Mu.m. 50% particle diameter of hollow particles (D ₅₀ ) More preferably 230nm or more, still more preferably 250nm or more. In addition, 50% of the particle diameter (D ₅₀ ) More preferably 10 μm or less, still more preferably 1 μm or less, particularly preferably 0.5 μm or less.

The 50% particle diameter of the hollow particles was calculated using a particle size distribution measuring apparatus (for example, MT3300EXII manufactured by Microtrac BEL corporation) by a laser diffraction method.

In the case where the hollow portion forming particles are template particles, the size of the template particles is substantially the same as the size of the hollow portions of the light scattering silica particles, and therefore, the template particles preferably have a 50% particle diameter (D ₅₀ ) Particles in the range of 200nm to 50. Mu.m. 50% particle diameter of template particle (D ₅₀ ) More preferably 230nm or more, still more preferably 250nm or more, still more preferably 10 μm or less, still more preferably 1 μm or less, particularly preferably 0.5 μm or less.

The 50% particle diameter of the template particles was calculated using a particle size distribution measuring apparatus (for example, MT3300EXII manufactured by Microtrac BEL corporation) by a laser diffraction method.

The hollow-portion-forming particles may have a spherical shape, an oval spherical shape other than a spherical shape, or the like, and may be partially aggregated or formed by aggregation of the hollow-portion-forming particles.

The hollow-forming particles are preferably mixed in the silica precursor dispersion or the silica precursor solution in the range of 0.1 to 40 mass%. If the amount of hollow-forming particles is too small, a plurality of hollow portions may not be contained in the particles, and if the amount is too large, scattering of the light-scattering silica particles may be saturated, and no further improvement in the light scattering effect may be observed. The use of the hollow portion in the range of 40 mass% or less enables the production of lightweight particles and the improvement of touch and feel, and thus enables the improvement of feel in use.

The silica precursor dispersion or silica precursor solution may optionally contain other ingredients. As other components, for example, sodium chloride, sodium sulfate, potassium chloride, potassium sulfate, and the like can be used for the purpose of adjusting pore diameter distribution.

The organic phase used in the continuous phase preferably has low solubility in the silica precursor dispersion or silica precursor solution, and more preferably has no solubility.

Examples of the organic liquid constituting the organic phase include saturated straight-chain hydrocarbons having 9 to 12 carbon atoms such as n-nonane, n-decane, n-undecane and n-dodecane; saturated branched hydrocarbons having 9 to 12 carbon atoms such as isononane, isodecane, isoundecane and isododecane; aliphatic hydrocarbons having 6 to 8 carbon atoms such as n-hexane, isohexane, n-heptane, isoheptane, n-octene, isooctene and the like; alicyclic hydrocarbons having 1 to 8 carbon atoms such as cyclopentane, cyclohexane and cyclohexene; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, propylbenzene, cumene, mesitylene, and tetrahydronaphthalene; ethers such as propyl ether and isopropyl ether; esters such as ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, n-pentyl acetate, isopentyl acetate, butyl lactate, methyl propionate, ethyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, and butyl butyrate; fluorine-containing compounds such as 1, 2-tetrafluoroethyl-2, 2-trifluoroethyl ether, and the like.

The number of these may be 1 alone or 2 or more. Among them, saturated straight-chain hydrocarbons having 9 to 12 carbon atoms such as n-decane, n-nonane, n-dodecane and n-undecane are preferable; saturated branched hydrocarbons such as isononane, isodecane, isoundecane and isododecane.

The flash point of the organic liquid constituting the organic phase is preferably 20 to 80 ℃, more preferably 30 to 60 ℃. In addition, an organic liquid which is nonflammable or flame retardant is preferable.

In the case of using saturated hydrocarbons having a flash point of less than 20 ℃ as the organic liquid, countermeasures in the working environment are required in terms of fire prevention because of the low flash point. By setting the flash point of the organic liquid to 20 ℃ or higher, the fire resistance can be improved and the working environment can be improved. On the other hand, the volatile property can be sufficiently obtained by setting the temperature to 80 ℃ or lower, and the organic liquid can be prevented from adhering to and mixing into the light-scattering silica particles when the light-scattering silica particles are recovered from the organic phase.

A surfactant is added as an emulsifier to the organic phase. Examples of the surfactant include anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, and the like.

Examples of the anionic surfactant include sodium fatty acid, alkyl sulfate, alkylbenzenesulfonate, and alkyl phosphate.

Examples of the cationic surfactant include alkyl trimethylammonium salts, dialkyl dimethylammonium salts, and alkyl benzyl dimethylammonium salts.

Examples of the amphoteric surfactant include alkyl dimethyl amine oxide and alkyl carboxyl betaine.

Examples of the nonionic surfactant include polyethylene glycol fatty acid esters, polypropylene glycol fatty acid esters, polyethylene glycol alkyl ethers, sorbitan fatty acid esters, polyoxyethylene alkylphenyl ethers, and polyoxyethylene alkyl ethers.

These surfactants may be used alone or in combination of 1 or more than 2. Among them, sorbitan fatty acid esters such as sorbitan monooleate, sorbitan dioleate, and sorbitan trioleate are preferable.

The amount of the surfactant to be used may be appropriately selected depending on the type of the surfactant, the HLB (Hydrophile-lipophile balance) which is an index indicating the degree of hydrophilicity or hydrophobicity of the surfactant, the particle diameter of the silica particles to be targeted, and other conditions. Specifically, the content of the organic phase is preferably in the range of 0.1 to 5.0 mass%, more preferably 0.1 to 3.0 mass%, and even more preferably 0.1 to 1.0 mass%.

The content of the surfactant in the organic phase is 0.1 mass% or more, whereby the emulsion can be uniformly emulsified and further stabilized. On the other hand, the content of 5.0 mass% or less prevents the surfactant from adhering to and mixing into the light-scattering silica particles as the final product. In the case where the viscosity of the dispersed phase is low, the concentration of the surfactant is preferably lower for uniform emulsification.

The emulsion is obtained by adding a dispersed phase to a continuous phase and stirring. The dispersed phase is preferably added while stirring the continuous phase.

As the stirring method, conventionally known methods can be used, and emulsifying apparatuses such as a homogenizer, a homogenizing mixer, a colloid mill, an ultrasonic emulsifying machine, and a homogenizing disperser can be used.

For example, in the case of emulsifying by using a homogenizer, stirring and emulsification may be performed under emulsification conditions such that a target droplet diameter can be formed.

For example, in the case of emulsifying by using a homogenizing mixer, the emulsifying may be carried out by stirring at a speed of 1000 to 24000rpm for 1 to 10 minutes.

The liquid temperature during stirring and emulsification is preferably 10 to 40 ℃, more preferably 10 to 35 ℃, and even more preferably 10 to 30 ℃.

Next, the obtained emulsion was solidified to precipitate silica, and a silica slurry containing silica containing hollow-portion-forming particles was obtained.

Examples of the curing method include adding an acid under stirring. Thereby, the pH of the silica precursor dispersion or the silica precursor solution is lowered, and primary particles of silica are precipitated. Since the precipitated primary particles aggregate, secondary particles of silica containing hollow particles are produced. The condition for adding the acid may be one in which spherical particles are obtained at the time of completion of gelation and the pH of the aqueous phase after two-phase separation is in the vicinity of neutral pH, preferably 7 to 10.

The acid used may be any of an inorganic acid and an organic acid, and is more preferably an inorganic acid such as sulfuric acid, hydrochloric acid, or carbonic acid, and carbon dioxide is most preferably used in view of ease of handling.

The reaction solution is separated into an oil phase and an aqueous phase in which silica having hollow particles formed therein is precipitated, and thus the oil phase is removed to obtain a silica slurry.

The removal of the oil phase can be performed by a conventionally known method, and examples thereof include decantation, reduced pressure filtration, membrane separation, and centrifugal separation.

Next, when the hollow-portion-forming particles are hollow particles, the obtained silica slurry is washed and dried. In the case where the hollow-portion-forming particles are template particles, the template particles are removed, and then washed and calcined.

The hollow portion forming particles will be described as hollow particles.

As a cleaning liquid for cleaning the silica slurry, water is exemplified; organic solvents such as ethanol, acetone, and diethyl ether.

The temperature of the cleaning liquid is preferably 10 to 100 ℃, more preferably 20 to 90 ℃, and still more preferably 30 to 80 ℃.

After the silica slurry is sufficiently washed, it is dried. The drying may be performed by a conventionally known method. Examples of the drying method include vacuum drying, natural drying, and warm air drying, and examples thereof include spray drying, air drying, tray drying, vacuum drying, and kiln.

The drying conditions may be any conditions that can remove and dry the cleaning liquid, and may be appropriately adjusted according to the drying method used.

The case where the hollow-forming particles are template particles will be described.

In the case of using the template particles, in the step of producing the light scattering silica particles using the hollow particles, the hollow particles are replaced with the template particles to produce silica particles, and then the template particles are removed and calcined.

The template particles decomposed by heat are heated at a temperature at which the template particles thermally decompose, and then the porous portions around the hollow portions are calcined to make the pores non-porous. Thereby, densification occurs around the hollow portion, and a closed cell structure is obtained. The calcination method may be a conventionally known calcination method, and examples thereof include an electric furnace and an oven.

The temperature at which the template particles are thermally decomposed is not particularly limited as long as the template particles can be removed, and is preferably in the range of 300 to 700 ℃. The thermal decomposition time is not particularly limited as long as the template particles can be removed, and may be arbitrarily set within a period of, for example, 1 second to 24 hours.

The calcination temperature for destroying the pores around the hollow portion is preferably 800 to 1300 ℃. The silica around the hollow portion can be densified by calcining at 800 ℃ or higher, and the particles can be prevented from sintering during calcining when the temperature is 1300 ℃ or lower. The calcination temperature is more preferably 900 ℃ or higher, still more preferably 1000 ℃ or higher, and still more preferably 1200 ℃ or lower, still more preferably 1100 ℃ or lower. The calcination time is not particularly limited as long as the silica around the hollow portion is densified and the hollow portion is closed, and may be arbitrarily set within a period of 1 second to 24 hours in view of the calcination means and production efficiency to be employed.

The heating may be performed continuously with the heating for decomposing the template particles and the heating for calcining, and the calcination may be performed by reheating the silica particles once returned to normal temperature after the template particles are removed by the heating.

The removal of template particles dissolved in an acid is performed by adding an acid to the silica slurry. Examples of the acid that can be used include inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid; organic acids such as acetic acid, perchloric acid, hydrobromic acid, trichloroacetic acid, dichloroacetic acid, methanesulfonic acid, benzenesulfonic acid, and the like. Among them, sulfuric acid is preferably used from the viewpoints of safety and equipment protection.

The acid is preferably added to the silica slurry at a pH of 3 or less. The template particles are thereby dissolved and removed from the silica, and voids originating from the template particles are formed inside the silica particles.

The pH is preferably 1.5 to 2.5, more preferably 1.5 to 2.0.

After the template particles are removed, the silica after the template particles are removed is washed.

The cleaning liquid for cleaning silica is the same as the above, and water is exemplified; organic solvents such as ethanol, acetone, and diethyl ether.

The silica is sufficiently washed and then calcined. By calcining the silica, a dense layer is formed around the hollow, defining a closed cell structure. The calcination method may be a conventionally known calcination method, and examples thereof include an electric furnace and an oven.

The calcination temperature is preferably 800 to 1300 ℃ as in the case of using the thermally decomposable template particles. The silica around the hollow portion can be densified by calcining at 800 ℃ or higher, and the particles can be prevented from sintering during calcining when the temperature is 1300 ℃ or lower. The calcination temperature is more preferably 900 ℃ or higher, still more preferably 1000 ℃ or higher, and still more preferably 1200 ℃ or lower, still more preferably 1100 ℃ or lower.

The calcination time is not particularly limited as long as the silica around the hollow portion is densified and the hollow portion forms closed pores, and may be arbitrarily set within a period of 1 second to 10 hours in view of the calcination means and production efficiency to be employed.

In the present invention, the surface of the light scattering silica particles may be modified. The surface modification may be performed during the production of the light-scattering silica particles, specifically, before the washing after the emulsion is solidified to precipitate silica, or may be performed using the obtained light-scattering silica particles, and is preferably performed in a state in which insoluble substances are not attached to the particle surfaces from the viewpoint of modification efficiency.

As the surface modification of the light scattering silica particles, for example, it is preferable to carry 1 or 2 or more surface treatment agents selected from the group consisting of silicones, silylating agents, fatty acids having 12 or more carbon atoms and metal salts thereof, and higher alcohols having 14 or more carbon atoms on the particle surfaces. By supporting these surface treatments, the light-scattering silica particles can be rendered hydrophobic.

The method for surface modification using the silicone, the silylating agent, the fatty acid having 12 or more carbon atoms, and the metal salt thereof is not particularly limited, and a known method can be used. There may be mentioned: a method of dry-treating silica particles with a surface treating agent; a method of wet-treating silica particles with a surface treating agent, which comprises immersing silica particles in a solution obtained by dissolving or dispersing the surface treating agent in a solvent such as water or an organic compound.

Specifically, as a method for supporting the organic silicon and the silylation agent on the light scattering silica particles, for example, the silica particles are stirred while spraying the surface treatment agent diluted as needed, and then heated and mixed at 100 to 400 ℃. As another method, there is a method of introducing vapor generated by heating the surface treatment agent to a boiling point or higher into silica particles under agitation in a fluidized bed.

In addition, as a method for supporting a fatty acid having 12 or more carbon atoms and a metal salt thereof on the light-scattering silica particles, for example, a soluble metal salt such as aluminum chloride or zinc chloride is added in a state where the light-scattering silica particles and the fatty acid coexist in water or an organic solvent, and the metal salt of the fatty acid is precipitated on the powder, whereby the light-scattering silica particles covered with the surface treatment agent are obtained.

As a method for supporting the light scattering silica particles with the higher alcohol having 14 or more carbon atoms, first, the light scattering silica particles are mixed with the higher alcohol having 14 or more carbon atoms, and the higher alcohol having 14 or more carbon atoms is attached to the particle surface.

Since the higher alcohol having 14 or more carbon atoms is solid or viscous liquid at ordinary temperature, it is preferable that the higher alcohol having 14 or more carbon atoms is dissolved or has low viscosity by heating and is mixed with the silica particles.

The reaction temperature and reaction time in the mixing step may be appropriately set as long as the higher alcohol having 14 or more carbon atoms is melted and attached to the silica particles.

After attaching a higher alcohol having 14 or more carbon atoms to the surfaces of the light-scattering silica particles, the surface of the silica particles is subjected to a heat treatment at 160 ℃ or higher, whereby the higher alcohol having 14 or more carbon atoms is bonded to the surfaces of the silica particles.

The reaction temperature in the bonding step is more preferably 165℃or higher, and still more preferably 170℃or higher. The upper limit is not particularly limited, but is preferably 300℃or less, more preferably 250℃or less, from the viewpoint of suppressing thermal decomposition of the higher alcohol having 14 or more carbon atoms as the raw material.

The heating method may be performed by a conventionally known method, and examples thereof include a method of heating by a heating device, and examples thereof include a henschel mixer, a double cone dryer, a noda mixer (Nauta mixer), and a vibration dryer. The heat treatment is preferably performed under an inert gas atmosphere or under reduced pressure.

The reaction time in the bonding step is preferably 2 to 8 hours. If the reaction time is 2 hours or longer, the condensation reaction of the light scattering silica particles with a higher alcohol having 14 or more carbon atoms is suitably carried out, and if it is 8 hours or shorter, the production can be carried out with high productivity.

The reaction time is more preferably 3 hours or more, and still more preferably 87 hours or less.

After heating, the mixture is naturally cooled to obtain light-scattering silica particles carrying higher alcohols having 14 or more carbon atoms.

As the mixing ratio of the light-scattering silica particles and the surface treatment agent, it is preferable that the loading amount of the surface treatment agent per unit specific area of the particles is 1 to 6. Mu. Mol/m ² Is mixed by way of the above. If the loading of the surface treatment agent is 1 mu mol/m ² As described above, the light scattering silica particles having sufficient hydrophobicity can be obtained. If the amount of the surface treatment agent is too large, it will not adhere to the particles, and the residual amount will increase, so that it is preferably 6. Mu. Mol/m ² The following is given.

The surface treatment agent is more preferably carried at a loading per unit specific area of the particles of 1.2mol/m ² The above-mentioned components are mixed, and more preferably 1.5. Mu. Mol/m ² The above is more preferably 5. Mu. Mol/m ² Hereinafter, it is more preferably 4. Mu. Mol/m ² The following is given.

The light-scattering silica particles of the present invention have a plurality of hollow portions having a closed-cell structure in the interior of spherical particles, and therefore have light-scattering properties, and the amount of silica per unit measurement cross-sectional area to be produced is 20mg/cm ² Can exhibit light scattering properties against both visible light and ultraviolet light.

If hollow particles and solid particles are mixed with the liquid of the liquid composition, there is a possibility that a concentration difference of the filler in the composition occurs when the hollow particles float and the solid particles settle. In order to obtain the scattering effect of light, it is desirable to uniformly disperse the hollow particles in the composition, and the hollow particles may be biased due to aggregation or the like, so that the scattering characteristics of the particles may not be sufficiently exhibited.

However, the light-scattering silica particles of the present invention have hollow portions having a closed-cell structure in spherical particles, and thus can be uniformly dispersed in the composition.

The light-scattering silica particles of the present invention can be used as a filler for cosmetics, white paint, ultraviolet-reflecting paint, light-diffusing film, film for film structures, film for agricultural greenhouses, heat-curable resin, ultraviolet-curable resin, thermoplastic resin, etc.

In addition, the cosmetic containing the light-scattering silica particles of the present invention can provide a sunscreen effect, and can be safely used on the skin without fear of deterioration of components due to photocatalysis.

In addition, when the light scattering silica particles of the present invention are contained in the ultraviolet curable resin, ultraviolet rays are diffused into the interior, and therefore can be compounded at a high concentration.

Examples

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. In the following description, the same descriptions are used for common components. Unless otherwise specified, "parts" and "%" refer to "parts by mass" and "% by mass".

Examples 2 to 3, 7, 8 and 11 are examples, and examples 1, 4 to 6, 9 to 10 and 12 to 13 are comparative examples. Examples 8 to 13 are application examples in cosmetic formulations.

Example 1

< preparation of emulsion >

To 1250g of pure water, 7g of an EO-PO-EO block copolymer (Pluronic F68 manufactured by ADEKA Co., ltd.) having a polyoxyethylene block (EO) and a polyoxypropylene block (PO) bonded thereto was added and stirred until dissolved. To this aqueous solution, 42g of n-dodecane was added, and the whole liquid was stirred until it became uniform by using a homogenizer manufactured by IKA corporation, to prepare a coarse emulsion.

The crude emulsion was emulsified twice at 400bar by using a high-pressure emulsifying machine (LAB 2000, manufactured by SMT Co.), to prepare a fine emulsion, and allowed to stand at room temperature (25 ℃) for 15hr.

< Shell formation in the first stage >

1300g of the fine emulsion obtained above was put into a glass reaction tank having a capacity of 2L, and diluted sodium silicate aqueous Solution (SiO) was added so that the pH became 2 ₂ The concentration is 10.4 percent, na ₂ O concentration 3.6%) 41g and 1M sulfuric acid while maintaining adequate agitation at 40 ℃.

While the liquid was sufficiently stirred, 1M aqueous sodium hydroxide solution was slowly added dropwise so that the pH became 6, to obtain an oil core-silica shell particle dispersion. The resulting oil core-silica shell particle dispersion is maintained and allowed to cure.

< Shell formation in the second stage >

The oil core-silica shell particle dispersion obtained in the first stage of shell formation was heated to 70 ℃ in its entirety, and 1M NaOH was slowly added while stirring, to set the pH to 9.

Then, a diluted sodium silicate aqueous Solution (SiO) was gradually added together with 0.25M sulfuric acid so that the pH became 9 ₂ The concentration is 10.4 percent, na ₂ O concentration 3.6%) 460g.

Thereafter, the mixture was cooled to room temperature to obtain a hollow silica precursor dispersion.

< filtration, drying, calcination >

The entire silica precursor dispersion was filtered by pressure filtration (pressure 0.28 MPa) using a 0.45 μm hydrophilic PTFE membrane filter.

The filtered cake was dried under nitrogen atmosphere at 60 ℃ for 1 hour, followed by drying at 400 ℃ for 4 hours (heating time of 5 ℃/min), and the organic component was removed, thereby obtaining a hollow silica precursor.

The shell was baked by calcining the obtained precursor at 900℃for 4 hours (heating time: 5 ℃ C./min) to obtain hollow silica particles (50% particle diameter: 1.6 μm, density measured using Ar: 0.98 g/cm) ³ The volume ratio of the hollow portion was 55 vol%).

Example 2

As the dispersed phase, the following slurries were used: sodium silicate No. 3 (sodium silicate aqueous solution, siO, manufactured by AGC Si-Tech Co., ltd.) ₂ /Na ₂ Distilled water for O (molar ratio) =3)Diluting to obtain SiO ₂ The concentration is 12 percent, and 0.3g/g-SiO of sodium chloride is added ₂ To 100 parts of the aqueous solution thus obtained, 0.35 parts of the hollow silica particles (50% particle diameter: 1.6 μm) produced in example 1 were mixed with stirring to obtain a slurry. SiO in sodium silicate No. 3 ₂ The amount of hollow silica particles added in 100 parts of the composition was 3 parts.

As the continuous phase, n-decane (HC-250, C, manufactured by Tosoh Co., ltd.) ₁₀ H ₂₂ ) A continuous phase obtained by dissolving 0.7% of sorbitan monooleate (IONET S80, manufactured by san yo chemical Co., ltd.) as a surfactant in advance.

A sodium silicate slurry containing hollow silica as a dispersed phase was added to the reactor by stirring n-decane containing a surfactant as a continuous phase using a homogenizer (manufactured by MICROTEC NICHION, physcotron, generator shaft NS-30 UG/20P) and emulsified at 7000rpm for 5 minutes.

The obtained emulsion was stirred by a stirrer (Three-One Motor, manufactured by tokyo nitromachine Co.), and carbon dioxide was blown into the emulsion at a rate of 2.0L/min for 20 minutes, whereby silica was precipitated.

Thereafter, the aqueous phase containing silica gel obtained by removing the oil phase was washed by decantation, and dried by a spray dryer (micro spray dryer B290 manufactured by Nihon BUCHI corporation) to obtain light scattering silica particles (volume ratio of hollow portion (calculated value) of 0.7 vol%).

The obtained light-scattering silica particles were photographed by a scanning electron microscope (JCM-7000, manufactured by Japanese electronics Co.). SEM images are shown in fig. 1.

Example 3

In the preparation of the dispersed phase, 0.58 parts of hollow silica particles were mixed, and light scattering silica particles (the volume ratio of the hollow portion (calculated value) was 1.3 vol%) were obtained in the same manner as in example 2. SiO in sodium silicate No. 3 ₂ The amount of hollow silica particles added in 100 parts of the composition was 5 parts.

Example 4

A commercially available porous spherical silica (SUNSPHERE H-53 manufactured by AGC Si-Tech Co., ltd.) was used.

Example 5

A commercially available porous spherical silica (SUNSPHERE H-51 manufactured by AGC Si-Tech Co., ltd.) was used.

Example 6

As the dispersed phase, the following slurries were used: sodium silicate No. 3 (sodium silicate aqueous solution, siO, manufactured by AGC Si-Tech Co., ltd.) ₂ /Na ₂ O (molar ratio) =3) diluted with distilled water to give SiO ₂ The slurry having a concentration of 20% and magnesium hydroxide (MAGSEEDS X-6F, manufactured by Shendao chemical industry Co., ltd., 50% particle diameter of 0.8 μm) as a template particle was stirred and mixed therein.

As the continuous phase, n-decane (HC-250, C, manufactured by Tosoh Co., ltd.) ₁₀ H ₂₂ ) 1.4% of sorbitan monooleate (IONET S80, manufactured by Sanyo chemical Co., ltd.) as a surfactant.

The surfactant-containing n-decane as a continuous phase was stirred by a homogenizer (made by MICROTEC NICHION, physcotron, generator shaft NS-30 UG/20P), and a magnesium hydroxide-containing sodium silicate slurry as a dispersed phase was added thereto and stirred and emulsified at 12000rpm for 5 minutes.

Thereafter, the template was removed by adding sulfuric acid to the aqueous phase containing silica gel obtained by removing the oil phase while stirring at room temperature until the pH was 2. Further, the template and the residual solvent were removed by stirring for 30 minutes while maintaining the aqueous phase at 80℃and adjusting the pH to 2 with sulfuric acid.

The slurry from which the template and the solvent were removed was washed by decantation and dried by a spray dryer (micro spray dryer B290 manufactured by Nihon BUCHI corporation) to obtain silica particles.

The obtained silica particles were photographed by a scanning electron microscope (JCM-7000, manufactured by Japanese electronics Co.). SEM images are shown in fig. 2.

Example 7

The light scattering silica particles with the surface hydrophobized were produced by the following production method.

10g of the light-scattering silica particles prepared in example 3 and 4.1g of behenyl alcohol (Calcol 220-80, manufactured by Kao corporation) were placed in a closed vessel, and the vessel was put into a hot water bath (water bath) set at 95℃to be heated and mixed for 2 hours.

Next, 5g of the heated mixture was measured and heated under reduced pressure at 180℃for 4 hours by a vacuum dryer (SVD-10P, sanyo Co.). Thereafter, natural cooling and recovery were carried out to obtain 4.7g of hydrophobized light-scattering silica particles.

Test example 1 ]

The following measurements were performed on the particles of examples 1 to 6. The results are shown in Table 1 and FIGS. 3 to 5.

1. Reflectivity of

The amount of silica per unit measured sectional area was calculated to be 20mg/cm by the following procedure ² Is used for the reflection rate of the water filter cake.

First, water was added to each silica powder in UNIPACK and mixed to prepare a silica water cake having no fluidity. The amount of water added is 1.1 to 1.5 times the oil absorption.

Next, the amount of silica per unit measurement cross-sectional area is 20 to 30mg/cm ² The water cake was filled into a powder sample dish, and the reflectance (reflectance a) of the water cake at wavelengths of 310nm and 600nm was measured using an ultraviolet-visible near infrared spectrophotometer UV-3100PC (manufactured by Shimadzu corporation). Thereafter, reflectance (reflectance b) at wavelengths of 310nm and 600nm was measured without filling the cuvette with a sample. The interpolation values of the reflectance a and the reflectance b were calculated, and the amount of silica per unit measurement cross-sectional area was set to 20mg/cm ² Reflectivity at that time.

After preparing a 1% aqueous slurry for the particles of example 3, the reflectances at the wavelengths of 310nm and 600nm were measured using an ultraviolet-visible near infrared spectrophotometer UV-3100PC in the same manner as described above. The results are shown in FIG. 5.

2. The inside of the particles has a hollow part of 200nm to 50 mu m

The particle powder was observed by an optical microscope (morph 4, manufactured by Malvern corporation) in a state immersed in boiled linseed oil, and when a scattering body having a size of 200nm to 50 μm and a contrast different from the surrounding was observed in the particle, it was evaluated that a hollow portion of 200nm to 50 μm was "present", and when the scattering body was not observed, it was evaluated that a hollow portion of 200nm to 50 μm was "absent".

The optical microscope images of the silica particles of examples 3, 4 and 6 are shown in fig. 3.

3. Volume ratio of hollow part of 200 nm-50 μm in particle

The volume ratio (%) of the hollow portion in the particle was obtained as follows. The volume ratio of the hollow portion is expressed as a percentage by dividing the total volume occupied by the hollow portion by the sum of the volume occupied by the silica and the total volume occupied by the hollow portion.

With the density measured using argon (Ar) gas for the silica particles and the true density of silica (2.2 g/cm) ³ ) The calculation was performed to obtain the result. The density measured using Ar gas was measured using a dry automatic densitometer (AccuPyc II 1340, manufactured by Shimadzu corporation).

The density measured using Ar gas was set to ρ (g/cm) ³ ) The volume ratio of the hollow portion is obtained by using a calculation formula of 100 to 100×ρ/2.2 (%).

4. Oil absorption (cm) ³ /100g)

The oil absorption was measured in accordance with JIS K5101 (2004).

The volume of boiled linseed oil per 100g of the sample when the whole sample was formed into one piece was determined by adding boiled linseed oil to the sample while kneading the whole silica particles as the sample into one piece.

5.50% particle size (. Mu.m)

The particle size distribution measuring apparatus (MT 3300EXII, manufactured by Microtrac BEL) was used to calculate a 50% volume-converted particle size (50% particle size).

6. Specific surface area (m) ² /g)

The specific surface area was determined by analyzing the results of measurement under a relative pressure of 0 to 0.99 based on the nitrogen adsorption method by the BET method using an automatic specific surface area/pore distribution measuring apparatus (TriStar II 3020 series, manufactured by shimadzu corporation).

7. Pore volume (cm) ³ /g)

The pore volume was determined as follows: the results of measurement by the BJH method under a relative pressure of 0 to 0.99 based on the nitrogen adsorption method were analyzed by an automatic specific surface area/pore distribution measuring apparatus (TriStar II 3020 series, manufactured by Shimadzu corporation) similarly to the specific surface area.

8. Average circularity (-)

Regarding the circularity, the area and circumference of the particle were obtained by using image analysis software attached to a particle image analysis apparatus (morphogi 4, manufactured by Malvern corporation) and were calculated by introducing the obtained area and circumference into the following formula. The average circularity was obtained by averaging the circularities of 3 ten thousand silica particles.

9. Tactile sensation

An appropriate amount (half of the amount of the spatula) of the particles was applied to the inside of the upper wrist, and the touch was confirmed with the fingertip.

The case where no crunching was perceived was evaluated as "a (good)", and the case where crunching was perceived was evaluated as "B (poor)".

10. Coefficient of static friction, coefficient of dynamic friction (-)

The friction coefficient was determined using a static/dynamic friction measuring machine "TL201Tt" (manufactured by Trinity-Lab Co.). The stylus was a urethane-made dummy finger, the load was 30gf, the scanning distance was 40mm, the scanning speed was 10mm/sec, the coated substrate was artificial leather SAPURARE (manufactured by IDEATEX JAPAN Co.), and the coating amount of silica particles in each example was 0.8. Mu.L/cm in terms of volume per unit area ² The coefficient of friction was measured. Among the obtained friction coefficients, an average value in a range of 1000msec to 4000msec is set as a dynamic friction coefficient.

The coefficient of static friction is obtained from the maximum value in the range of 0msec to 1000 msec.

11.a ^* Value (-)

For the particles of examples 3 and 4, a was determined ^* Values.

Mixing iron (III) oxide powder (manufactured by Kanto chemical Co., ltd., high purity, reddish brown powder, a) ^* Value: 14.9 20, 40, 60 or 80% of the total amount of the powder particles, and mixing the powder particles to obtain a mixed powder. The mixed powder was poured into a measuring dish (diameter 35 mm. Times. Height 15 mm) so that the volume of the mixed powder became half or more, and the mixture was measured using a spectrocolorimeter (SE 7700, manufactured by Nippon electric color industry Co., ltd.).

A is that ^* The value indicates the intensity of the color, and the larger the +side, the more red and the larger the-side, the more green. When mixing iron (III) oxide powder in a proportion of 40%, if a ^* When the value is 6.0 or less, it can be judged that the color (red) of the iron (III) oxide is suppressed.

The results are shown in FIG. 4.

TABLE 1

From the results in Table 1 and FIGS. 1 to 3, it can be seen that: the light-scattering silica particles of examples 2 and 3 had a hollow portion having a closed-cell structure inside, and were light-scattering for both visible light and ultraviolet light when measured using a water cake.

The light-scattering silica particles of example 3 showed a reflectance a of 52.6% immediately after the production of the water cake (see table 1), and also showed 51.0% after being kept in a state where moisture was not volatilized for 1 week. The light-scattering silica particles of example 3 showed the reflectance B of 43.8% (see table 1) immediately after the preparation of the water cake and 42.1% even after the retention for 1 week. When the light scattering properties of the 1% aqueous slurry were measured by the above method, the light scattering silica particles of example 3 showed a reflectance a of 24.4% and a reflectance B of 20.6% (see fig. 5). Further, even after being kept in a 1% aqueous slurry for 1 week, the reflectance a was about 23% and the reflectance B was about 20%.

Thus, it can be said that the dry powder has light scattering properties for both visible light and ultraviolet light in the dry state, and as shown in fig. 4, the dry powder also has light scattering properties.

The hollow silica particles (example 1) were significantly different from the other particles (examples 2 to 6) in touch feeling, and were also different in dynamic friction coefficient and static friction coefficient. It can be seen that: the light scattering silica particles of examples 2 and 3 had smooth touch feeling and also had excellent feeling in use.

< test example 2>

The following measurements were performed on the particles of examples 3 and 7. The results are shown in Table 2.

12. Water repellency (-)

To a beaker (10 mL capacity) weighing 8g of water was added calmly 0.05g of the particles. Thereafter, the particles were tapped 20 times to spread the particles sufficiently on the water surface, and in this state, they were left standing at room temperature.

The solution was visually observed every 1 day, and the state of suspended/settled particles in the solution was evaluated. The case where particles were suspended or settled after 1 day of standing was evaluated as "C", the case where particles were suspended or settled after 2 to 6 days of standing was evaluated as "B", and the case where particles were not suspended or settled even after 7 days of standing was evaluated as "a". It was determined that "B" was superior in water repellency to "C" and "A" was superior in water repellency to "B".

13. Stability in oil (-)

4mL of water and 4mL of liquid paraffin (product code: 122-04775, fuji photo-alignment film and Wako pure chemical industries, ltd.) were weighed into the same container (13.5 mL-capacity capped transparent bottle), and 0.05g of particles was added to the 2-layer solution, followed by shaking for 20 times. Thereafter, the mixture was allowed to stand at room temperature.

The solution was visually observed every 1 day to evaluate the presence or absence of settled particles in the aqueous phase. The case where the particles were settled in the aqueous phase after 1 day of standing was rated as "C", the case where the particles were settled in the aqueous phase after 2 to 6 days of standing was rated as "B", and the case where the particles were not settled in the aqueous phase even after 7 days of standing was rated as "a". The oil having a "B" ratio to "C" was judged to be excellent in stability, and the oil having a "ratio to" B "was judged to be excellent in stability.

TABLE 2

From the results in table 2, it can be seen that: the hydrophobized light-scattering silica particles (example 7) exhibited sufficiently high hydrophobicity and were excellent in water repellency and stability in oil.

Examples 8 to 10

Powder face powder was prepared according to the composition described in table 3 below.

(manufacturing method)

Using a Henschel MIXER (HANIL ELECTRIC CO., LTD, hanil MIXER, model: LM-110T), the ingredients were mixed 3 times for 30 seconds until uniformity was achieved, thereby obtaining a powdery plop powder.

TABLE 3

TABLE 3 (compounding amount: mass%)

Composition of the components	Example 8	Example 9	Example 10
				Hydrogenated polydimethylsiloxane treating talc (-Bunge 1)	89.59	89.59	94.59
Zinc laurate (, 2)	5.00	5.00	5.00
				Silica particles of example 3	5.00	-	-
Silica particles of example 4	-	5.00	-
				Yellow iron oxide (, 3)	0.30	0.30	0.30
Red ferric oxide (, 4)	0.10	0.10	0.10
				Black iron oxide (, 5)	0.01	0.01	0.01
Totalizing	100	100	100

Details of the respective components in table 3 are shown below.

(1) treatment of talc with hydrogenated polydimethylsiloxane: talc DN-SH (Dakai chemical Co., ltd.)

(. Sub.2) zinc laurate: powder base L (daily oil Co.)

(. About.3) yellow iron oxide: sunPURO Yellow Iron Oxide C339001 (Sun Chemical Corp.)

(. Sub.4) red iron oxide: sunPURO Red Iron Oxide C338021 (Sun Chemical Corp.)

(5) black iron oxide: sunPURO Black Iron Oxide C337001 (Sun Chemical Corp.)

Examples 11 to 13

A water-in-oil BB cream was prepared according to the composition shown in Table 4 below. BB cream is an abbreviation of Bletish film or Beauty film, and is a multifunctional cosmetic which can be used as a face beautifying liquid, a moisturizing cream, a basic color cosmetic, a foundation and a sun protection.

(manufacturing method)

1) Using a dispersion stirrer (manufactured by PRIMIX corporation, labolutton, model: homodisperser type 2.5), the ingredients of group a were mixed in a uniform manner at 700rpm for 3 minutes to give a group a mixture.

2) The components of group B were mixed in a uniform manner at 700rpm for 3 minutes using a dispersing stirrer to obtain a group B mixture, which was mixed with the group A mixture to obtain a first composition.

3) The components of group C were mixed 3 times for 30 seconds in a uniform manner using a henschel mixer to obtain a group C mixture, which was mixed with the first composition to obtain a second composition.

4) The components of group D were mixed in a uniform manner at 700rpm for 3 minutes using a dispersing stirrer to obtain a mixture of group D.

5) The second composition was stirred at 5000rpm while adding the mixture of group D using a dispersing stirrer, and emulsified for 3 minutes, thereby obtaining a water-in-oil type BB cream.

TABLE 4

Table 4 (amount of blended: mass%)

Details of the respective components in table 4 are shown below.

(. About.6) cyclopentasiloxane: KF-995 (Xinyue chemical industry Co., ltd.)

(. About.7) isotridecyl isononanoate: saracos 913 (Nisshin OilliO Group company)

(-8) octyl methoxycinnamate: nomcoat TAB (Nisshin OilliO Group company)

(. About 9) hydrogenated polyisobutene: PARLEAM 4 (daily oil Co.)

(. About.10) (PEG-12 polydimethylsiloxane/PPG-20) crosslinked polymer, octyl polymethylsiloxane: DOWSIL DC EL-7040Hydro Elastomer Blend (Daochi Japanese Co., ltd.)

(. About.11) lauryl PEG-10 tris (trimethylsilyl) silylethyl polydimethylsiloxane: DOWSIL ES-5300Formulation Aid (Japanese Kodao Chemie Co., ltd.)

(. About.12) sorbitan sesquistearate: cosmol 182V (Nisshin OilliO Group company)

(. About.13) polyglyceryl isostearate-2: cosmol 41V (Nisshin OilliO Group Co.)

(. About.14) Quaternium-18 bentonite: S-Ben W (HOJUN Co.)

(. About 15) hydrogenated polydimethylsiloxane treatment of talc: talc DN-SH (Dakai chemical Co., ltd.)

Titanium oxide, aluminum hydroxide, stearic acid (16): ST-705SA (titanium industry Co., ltd.)

(17) treatment of titanium oxide with hydrogenated polydimethylsiloxane: titanium DN-SH (2) (Dakai chemical Co., ltd.)

(. About.18) yellow iron oxide: sunPURO Yellow Iron Oxide C339001 (Sun Chemical Corp.)

(. About.19) red iron oxide: sunPURO Red Iron Oxide C338021 (Sun Chemical Corp.)

(. About.20) black iron oxide: sunPURO Black Iron Oxide C337001 (Sun Chemical Corp.)

(. About.21) butanediol: 1, 3-butanediol (Daxiaolu)

(-Rg22) PEG/PPG/polytetramethylene glycol-8/5/3 Glycerol: WILBRIDE S-753 (daily oil Co.)

(. About.23) sodium chloride: sodium chloride (Guandong chemical Co., ltd.)

(. About.24) phenoxyethanol: phenoxyethanol S (Synthesis company of four-day city)

The PEG is polyethylene glycol, and the PPG is polypropylene glycol.

< test example 3>

Color difference Δe was measured for the powdery face powders of examples 8 to 10, and freckle masking properties were evaluated for the water-in-oil type BB creams of examples 11 to 13. The results are shown in Table 5.

14. Color difference ΔE (-)

To 0.5g of powdered face powder, 200. Mu.L of simulated sebum was added and mixed. Here, the sebum simulator refers to a mixture of tri (caprylic/capric glyceride)/octyldodecyl myristate/oleic acid/squalane=33.3%/33.3%/20.0%/13.4%.

Tris (caprylic/capric glycerides): O.D. O (Nisshin OilliO Group Co.)

Octyl dodecyl myristate: EXCEPARL OD-M (Huawang Co., ltd.)

Oleic acid: lunac O-V (Huawang Co., ltd.)

Squalane: phytosqualane (SOPHIM)

The color change of the obtained powder was supplied to a colorimeter (ZE 6000, japan electrochromic industry company) and evaluated based on the color difference Δe from the face powder to which no sebum-simulating powder was added.

The smaller Δe, the more suppressed the color change when it comes into contact with sebum on actual skin is judged.

15. Masking of freckle (-)

On a freckle plate (FR-40, manufactured by Beaulax Co.) to be 2.5mg/cm ² BB cream is applied and allowed to dry sufficiently. Thereafter, the masking property of the freckle was confirmed, and the case where the freckle was difficult to observe was designated "a", the case where the freckle was thin was designated "B", and the case where the freckle was clearly confirmed was designated "C".

Judging as follows: the "B" can mask the appearance defect such as freckle on the actual skin as compared with the "C" and the "a" can mask the appearance defect such as freckle on the actual skin as compared with the "B".

TABLE 5

From the results of table 5, it can be judged that: the powdery plon powder (example 8) containing the light-scattering silica particles of example 3 had a low Δe, and the color change was suppressed when the plon powder was actually contacted with sebum. It is also known that: the freckle masking property of the BB cream (example 11) containing the light-scattering silica particles of example 3 was a, and it was expected that the freckle-masking effect could be achieved in actual skin.

The present invention has been described in detail and with reference to specific embodiments, but it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof. The present application is based on japanese patent application (japanese patent application publication No. 2021-113071) filed 7/2021, the contents of which are incorporated herein by reference.

Claims

1. A light-scattering silica particle having light scattering properties,

the cumulative 50% particle diameter based on the volume of the light-scattering silica particles is 1 to 500 [ mu ] m, and the average circularity is 0.80 or more,

2. The light-scattering silica particles according to claim 1, wherein the oil absorption of the light-scattering silica particles is 100cm ³ And/or 100 g.

3. The light-scattering silica particle according to claim 1 or 2, wherein the hollow portion is defined by hollow particles.

4. The light-scattering silica particles according to any one of claims 1 to 3, wherein the hollow portion has a size of 200nm to 50 μm.

5. The light-scattering silica particles according to any one of claims 1 to 4, wherein an amount of silica per unit measurement cross-sectional area when the light-scattering silica particles are used is 20mg/cm ² The reflectance B of the water cake at the visible light wavelength of 600nm is more than 30%.

6. The light-scattering silica particles according to claim 5, wherein a difference (a-B) obtained by subtracting the reflectance B from the reflectance a is 3% or more.

7. The light-scattering silica particles according to any one of claims 1 to 6, wherein 1 or 2 or more kinds selected from the group consisting of silicones, silylating agents, fatty acids having 12 or more carbon atoms and metal salts thereof, and higher alcohols having 14 or more carbon atoms are supported on the surface of the light-scattering silica particles.

8. A method for producing light-scattering silica particles, which is a method for producing light-scattering silica particles having light scattering properties,

dispersing hollow-forming particles in a silica precursor dispersion or a silica precursor solution, emulsifying the dispersion to obtain droplets, and solidifying the droplets.

9. The method for producing light-scattering silica particles according to claim 8, wherein the hollow-forming particles are dispersed in the silica precursor dispersion or the silica precursor solution in a range of 0.1 to 40 mass%.

10. The method for producing light-scattering silica particles according to claim 8 or 9, wherein the hollow-portion-forming particles are hollow particles.

11. The method for producing light-scattering silica particles according to claim 10, wherein the hollow particles are at least 1 kind among hollow silica particles and glass hollow spheres.

12. The method for producing light-scattering silica particles according to claim 10 or 11, wherein the hollow portion inside the hollow particles has a size of 200nm to 50 μm.

13. The method for producing light-scattering silica particles according to claim 8 or 9, wherein the hollow-forming particles are template particles, the template particles are removed after the droplets are solidified, and calcination is performed at 800 to 1300 ℃.

14. The method for producing light-scattering silica particles according to claim 13, wherein the size of the template particles is 200nm to 50 μm.

15. The method for producing light-scattering silica particles according to any one of claims 8 to 14, wherein 1 or 2 or more kinds selected from the group consisting of silicones, silylating agents, fatty acids having 12 or more carbon atoms and metal salts thereof, and higher alcohols having 14 or more carbon atoms are attached to the surface of particles obtained by solidifying the droplets.

16. A cosmetic comprising the light-scattering silica particles according to any one of claims 1 to 7.